挤压铸造工艺制备SiC3D/Al复合材料辅助模具研究

Design of Assistive Mould Used in Preparation of 3-D Reinforced MMCs by Squeeze Casting

使用挤压铸造工艺,采用新型辅助模具成功实现高陶瓷体积分数SiC_(3D)/Al复合材料的制备,研究了辅助模具上开孔位置、孔径大小对复合材料致密度的影响规律,并分析了挤压铸造过程中辅助模具开裂导致浸渗失败的原因。试验结果表明,当开孔面积比大于20%时,无论是面板中心位置开孔、四周位置开孔还是全位置均布开孔,其浸渗致密度均在95%以上。当面板开孔孔径小于1 mm时,复合材料的致密度不足75%,而开孔孔径大于12 mm的复合材料浸渗率均在95%以上,开孔孔径对浸渗结果影响显著。建立了辅助模具厚度方向临界强度计算方法,针对本文所用90 mm×90 mm×28 mm辅助模具,其面/背板的连接强度应大于4.82 KN方能防止其挤压铸造过程中的开裂,壁厚为5 mm的焊接辅助模具和整体辅助模具都能满足上述强度要求。

SiC3D/Al composites were prepared successfully by squeeze casting with the help of assistive moulds.Effects of the location and the diameter of the holes in the assistive mould faceplates on the density of the composites were investigated.The reason of the composite failure caused by the crack of assistive moulds was analyzed.The result shows whether the holes were located in the middle of,or around the perimeter of,or equispaced on assistive mould faceplates,the density of the composites would be over 95%.The density of the composites would be lower than 75%when the diameter of the holes was samller than 1 mm,and it would be higher than 95%when the diameter was bigger than 12 mm,which shows the hole diameter significantly affects the composite density.What’s more,a method for calculating the concrete strength of the assistive mould along the thickness direction was found.For the 90×90×28 mm^3 assistive mould used in this study,the concrete strength is 4.82 KN,which can be satisfied by welded and cast assistive moulds.